Currently available Standard High Volume (SHV) commodity computer components, such as processors, single in-line memory modules (SIMMs), peripheral devices, and other specific components, have made it possible to easily and cheaply design and build computer systems including personal computers and multiprocessor servers. While it is possible to create custom personal computer and server designs which may be more clever and efficient than systems fashioned from standard components, the benefits of volume pricing and availability provided by the use of commodity components imparts a significant advantage to computer systems constructed from commodity SHV components.
FIG. 1 provides a simple block diagram of a standard high volume (SHV) symmetric multiprocessing (SMP) computer system employing currently available commodity components. The design shown employs Intel Pentium.RTM. Pro.TM. processors and a high-performance bus and chipset, such as an Intel processor bus and 8245GX chipset, respectively, that are intended to be the SHV companions of the Pentium.RTM. Pro processor.
The system as shown in FIG. 1 includes up to four processors 101 connected to a high-bandwidth split-transaction bus 103. A system memory 105 is connected to bus 103 through a memory controller chipset 107. Connection to standard PCI devices, not shown, is provided through PCI I/O interfaces 109. As stated above, all of these components are currently available commodity components. The characteristics of the SHV architecture shown in FIG. 1 include:
Support for up to four processors 101 and two PCI interfaces 107 on a single bus 103. PA1 A high-performance bus topology operating at 66 Mhz with a 64 bit datapath, and capable of a sustained data transfer rate of 533 MB/s. PA1 A memory controller 107 consisting of two chips 111 and 113 which present two loads to bus 103. PA1 processor bus-to-PCI I/O bridges (IOBs) 109 that will peak at a data transfer rate of 132 MB/s with a sustained data transfer rate of about 80 MB/s.
The architecture shown in FIG. 1, constructed of commodity components, simplifies the design of reasonably powerful multiprocessor system having up to four processors. However, the Pentium.RTM. Pro processor/processor bus architecture described above does not permit expansion beyond four processors. Other improvements to the system thus far described are also possible.